This invention relates to apparatus for placing a band of shrinkable plastic film over one or more objects southt to be banded. After the band has been placed over the object or objects it is shrunk to fit tightly.
The use of plastic neck bands of shrinkable plastic film for sealing bottles of medicine, toiletries, foodstuff and beverages is well known. In addition to serving as tamper proof or secondary seals, such bands may also be used to fasten two or more articles or objects together, or to fasten a label to an article. The bands may be made of any suitable transparent or opaque plastic film which can be shrunk to form a tight fitting seal around the object or objects sought to be banded. Although films which shrink upon coming in contact with moisture are known, the preferred materials are heat shrinkable films of, for example, polyolefin or polyvinylchloride (PVC).
Machines for placing bands of shrinkable film over bottles and the like are known. Conventionally, such machines include a conveyor which carries the bottles to the banding station. There the banding machine places a heat shrinkable band over the neck of the bottle, after which the conveyor carries the bottle through a tunnel heater which causes the film to shrink tightly around the object to be banded.
Depending on their specific use, banding machines must be capable of placing the bands over the objects accurately and at a rate of speed sufficient to keep pace with other packaging operations, since shut down of the banding machine, for even a relatively short period of time, will cause substantial disruption of continuous filling and packaging operations. Prior art machines tend to jam, to place the bands in an inaccurate manner, and to be too slow. Furthermore, since shrink-tubing, from which the individual bands are usually cut, is normally supplied in coils of flattened tubing crimped at the two edges, a persistent problem in the prior art has been to keep the bands open and properly aligned with the objects to be banded. These problems grow more acute as the film gets thinner and the bands get wider in diameter.
It is therefore an object of this invention to provide apparatus capable of placing bands of thin shrinkable film over an object rapidly and dependably.